New experiments may reconcile conflicting studies regarding the peacock’s allure

His shimmering train of feathers tipped with eye-shaped spots ranks among the most cited examples of what Darwin called sexual selection. In this singles-bar approach to evolution, flashy plumage and other ornaments arise not because they enhance survival of the fittest but because they favor reproduction of the sexiest.

Basic principles aren’t in doubt for the peacock exemplar. Yet “everybody uses it without knowing much about how it works,” says Roslyn Dakin of Queen’s University in Kingston, Canada.

Watching how peafowl courtship played out in three clusters of free-roaming birds, she found that shimmying a train with especially high numbers of eyespots did not — repeat, did not — seem to improve a male’s chances of dazzling a female into mating.

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